.gif)
Green Lake (New York)
Encyclopedia
Green Lake is the larger of the two lakes in Green Lakes State Park
, which lies about 9 miles (14.5 km) east of downtown Syracuse
in Onondaga County, New York
. Round Lake is the smaller lake located west of Green Lake. Both lakes are meromictic
, which means that there is no seasonal mixing of surface and bottom waters. Meromictic lakes are fairly rare; they've been extensively studied, in part because their sediments can preserve an historical record extending back thousands of years, and because of the euxinic (anoxic
, sulfidic) conditions which can form in the deep water.
, and since 1933 large quantities of sand have been dumped on the shore of the north end to create a swimming area.
(a separation in a body of water due to differing chemistries) is present between 18–20 meters depth. The water below the chemocline is anoxic
and sulfidic, and at the chemocline there is a dense layer of purple sulfur bacteria
which makes the water appear pink. The purple sulfur bacteria thrive in the anoxic waters and utilize the sulfide from the deeper water in their photosynthesis.
The color of the lake is created by the large amount of total dissolved solids (from the groundwater input) which disperse the sunlight creating a greenish color. Annual whiting events occur in FGL, due to the large Synechococcus
population in the lake. Calcite
precipitates in microenvironments surrounding the Synechococcus and this is believed to dominate the whiting events. Calcite precipitation is common year round at FGL, and this leads to the carbonate crust that surrounds most of the lake, and covers branches and other material that falls below the surface. Dead Man's Point is a notable example of this, and is classified as a thrombolitic bioherm.
and during times of environmental stress. (i.e. mass extinction events). During these times it has been suggested that the oceans became anoxic and possibly sulfidic in the deep water. Information about past environments can be gained through studying isotopic, chemical, and biological compositions of modern day FGL. FGL is the subject of multiple scientific studies per year. Recent work by Lee Kump at Penn State University has been featured on the television shows Nova: scienceNOW and National Geographic, relating FGL to the end-Permian mass extinction.
Green Lakes State Park
Green Lakes State Park is a New York State Park located east of Syracuse in the Town of Manlius. The park is strikingly scenic, and has a "masterpiece" golf course designed by Robert Trent Jones very early in his career. Green Lake itself is perhaps the most studied meromictic lake – one in...
, which lies about 9 miles (14.5 km) east of downtown Syracuse
Syracuse, New York
Syracuse is a city in and the county seat of Onondaga County, New York, United States, the largest U.S. city with the name "Syracuse", and the fifth most populous city in the state. At the 2010 census, the city population was 145,170, and its metropolitan area had a population of 742,603...
in Onondaga County, New York
Onondaga County, New York
Onondaga County is a county located in the U.S. state of New York. As of the 2010 census, the population was 467,026. The county seat is Syracuse.Onondaga County is part of the Syracuse, NY Metropolitan Statistical Area....
. Round Lake is the smaller lake located west of Green Lake. Both lakes are meromictic
Meromictic
A meromictic lake has layers of water that do not intermix. In ordinary, "holomictic" lakes, at least once each year there is a physical mixing of the surface and the deep waters...
, which means that there is no seasonal mixing of surface and bottom waters. Meromictic lakes are fairly rare; they've been extensively studied, in part because their sediments can preserve an historical record extending back thousands of years, and because of the euxinic (anoxic
Hypoxia (environmental)
Hypoxia, or oxygen depletion, is a phenomenon that occurs in aquatic environments as dissolved oxygen becomes reduced in concentration to a point where it becomes detrimental to aquatic organisms living in the system...
, sulfidic) conditions which can form in the deep water.
Description
Green Lake reaches a maximum depth of 195 feet. Deep lakes tend to appear bluish because the wavelengths of light that can penetrate (and be dispersed at) great depths are those closer to the blue end of the spectrum. Because of its depth and the high salinity of the basin waters, the lake is Meromictic and does not turn over and intermix waters like many other lakes in this region do. Green Lake's cold and dense bottom waters tend to stay separate from the shallower, warmer waters. Because of this, sediment sinks and collects in the bottom and virtually doesn't decay. Since the sediment is not kicked up by mixing, the lake does not take on a muddy, turbid appearance like other lakes do. Meromictic lakes also have still, mirror-like waters. Green Lake is no exception here, as its tranquil, reflective water makes for great photography. The Lake resides in an ancient river basin, carved deeper into the limestone bedrock by the last ice age. Limestone, an easily dissolved sedimentary rock, saturates the Lake's waters with calcium carbonate, a bluish salt solution. The lake which resembles a large river in shape, is unusually deep for its size and was regarded as being sacred by the native Onondaga tribe, which originally settled in the area.History
Fayetteville Green Lake (FGL) was the first lake in North America identified as meromictic, and is the best studied meromictic lake in the world with records dating back to 1839. Green Lake was referred to as Lake Sodom by Vanuxem, who was the first to study Green Lake in 1839, and the presence of sulfide in the deeper waters of the lake was known by 1849. FGL is believed to have formed as a plunge pool during the late Wisconsin stage of glaciation at the base of a waterfall formed by the retreating glaciers, which is the reason for its extreme depth relative to a small surface area. The outflow for FGL runs underneath the Erie Canal, which is located within 300m of the north shore of the lake. FGL is currently located in Green Lakes State ParkGreen Lakes State Park
Green Lakes State Park is a New York State Park located east of Syracuse in the Town of Manlius. The park is strikingly scenic, and has a "masterpiece" golf course designed by Robert Trent Jones very early in his career. Green Lake itself is perhaps the most studied meromictic lake – one in...
, and since 1933 large quantities of sand have been dumped on the shore of the north end to create a swimming area.
Biogeochemistry
Fayetteville Green Lake (FGL) is located in the Oswego River-Lake Ontario drainage system; and receives surface water from Round Lake. The water column is chemically stratified into an oxygenated upper portion (mixolimnion) and a euxinic deeper portion (monimolimnion). The stratification is maintained through the large input of ground water rich in dissolved solids to the deeper portion of the lake. The difference in the dissolved solids (Ca, Mg, SO4) between the water input to the surface and water input to the deep creates the permanent stratification observed. FGL has a sulfate concentration around 13.5 mmol/L (about half that of modern seawater) which is derived from groundwater input to the deep portion of the lake. A well-developed chemoclineChemocline
A chemocline is a cline caused by a strong, vertical chemistry gradient within a body of water. A chemocline is analogous to a thermocline, the border at which warmer and cooler waters meet in an ocean, sea, lake, or other body of water...
(a separation in a body of water due to differing chemistries) is present between 18–20 meters depth. The water below the chemocline is anoxic
Hypoxia (environmental)
Hypoxia, or oxygen depletion, is a phenomenon that occurs in aquatic environments as dissolved oxygen becomes reduced in concentration to a point where it becomes detrimental to aquatic organisms living in the system...
and sulfidic, and at the chemocline there is a dense layer of purple sulfur bacteria
Purple sulfur bacteria
The purple sulfur bacteria are a group of Proteobacteria capable of photosynthesis, collectively referred to as purple bacteria. They are anaerobic or microaerophilic, and are often found in hot springs or stagnant water. Unlike plants, algae, and cyanobacteria, they do not use water as their...
which makes the water appear pink. The purple sulfur bacteria thrive in the anoxic waters and utilize the sulfide from the deeper water in their photosynthesis.
The color of the lake is created by the large amount of total dissolved solids (from the groundwater input) which disperse the sunlight creating a greenish color. Annual whiting events occur in FGL, due to the large Synechococcus
Synechococcus
Synechococcus is a unicellular cyanobacterium that is very widespread in the marine environment. Its size varies from 0.8 µm to 1.5 µm...
population in the lake. Calcite
Calcite
Calcite is a carbonate mineral and the most stable polymorph of calcium carbonate . The other polymorphs are the minerals aragonite and vaterite. Aragonite will change to calcite at 380-470°C, and vaterite is even less stable.-Properties:...
precipitates in microenvironments surrounding the Synechococcus and this is believed to dominate the whiting events. Calcite precipitation is common year round at FGL, and this leads to the carbonate crust that surrounds most of the lake, and covers branches and other material that falls below the surface. Dead Man's Point is a notable example of this, and is classified as a thrombolitic bioherm.
Geologic Significance
The meromictic character of FGL is believed to represent a possible analog to ancient ocean environments during the PrecambrianPrecambrian
The Precambrian is the name which describes the large span of time in Earth's history before the current Phanerozoic Eon, and is a Supereon divided into several eons of the geologic time scale...
and during times of environmental stress. (i.e. mass extinction events). During these times it has been suggested that the oceans became anoxic and possibly sulfidic in the deep water. Information about past environments can be gained through studying isotopic, chemical, and biological compositions of modern day FGL. FGL is the subject of multiple scientific studies per year. Recent work by Lee Kump at Penn State University has been featured on the television shows Nova: scienceNOW and National Geographic, relating FGL to the end-Permian mass extinction.
External links
- "The Underwater World of Green Lakes", video obtained using a robotic submarine by Dr. Mark A. Teece